1. Field of the Invention
The present invention relates to a magnetic storage device having a ramped-loading-type head suspension.
2. Description of the Related Art
A head suspension, which is generally used with a disk unit, such as a floppy disk unit or a hard disk unit, includes a support beam, a spacer and a gimbal. The gimbal is formed with higher flexibility than that of the support beam and is mounted on the portion near to one end (the free end) of the support beam. Specifically, the gimbal has a base portion with a tongue portion pivotally coupled thereto through a pivotal portion arranged on the side nearer to the distal end of the support beam. Also, the gimbal is coupled to the support beam at the end of the base portion of the gimbal arranged nearer to the proximal end opposite to the free end of the support beam. A magnetic head slider is further mounted on the surface of the tongue portion of the gimbal. Also, the spacer is formed with a boss and is coupled to the portion near to the other end of the support beam, and the head suspension is connected to a carriage arm through the boss. The driving force of an actuator is transmitted to the carriage arm by a transmission mechanism such as a lead screw, a steel belt or a spiral cam. Thus, the head suspension supporting the head slider thereon is driven via the carriage arm so that a magnetic head of the head slider can write and/or read data on a storage medium such as a magnetic disk having a magnetic film on the surface thereof.
The portions of the magnetic head slider and the storage medium near to each other will be now described in detail.
The support beam includes a rigid portion and a spring portion having a bent portion having an elasticity (spring nature). The spring portion is located near to the proximal end of the support beam supported by the carriage arm. The rigid portion, on the other hand, is located nearer to the distal end than the spring portion, and is generally formed with a rib on each side edge thereof to improve the rigidity. Also, a pivot is formed in the portion of the distal end of the support beam where the gimbal is mounted, and the tongue portion of the gimbal can rock on the pivot.
An urging force generated in the spring portion of the support beam is exerted on the head slider through the gimbal so that head slider is urged toward the storage medium while being able to rock on the pivot. This allows the head slider to follow the movement of the storage medium.
The head slider flies above the surface of the storage medium at a predetermined distance (typically about 20 nm) as the flying force floatation force, generated on the air-bearing surface of the head slider by the air flowing between the surface of the rotating storage medium and the air-bearing surface of the head slider, is balanced-by the urging force exerted on the head slider by the head suspension.
When the storage medium stops rotating, therefore, the head slider will not receive the flying force and will contact the surface of the storage medium. In such a magnetic storage device, it is necessary to protect a ring-shaped data zone of the storage medium, for data to be recorded, from the head slider when the storage medium is not rotating. A loading/unloading mechanism for carrying out such a protection is divided into two major types; a CSS (contact start stop) type and a ramped loading type.
In the CSS-type loading/unloading mechanism, the head slider is moved to the CSS zone located inside the data zone of the storage medium when the storage medium stops rotating. When the storage medium starts rotating and the head slider flies, on the other hand, the head slider moves to the data zone again. In the ramped-loading-type loading/unloading mechanism, in contrast, the head slider is moved onto a ramp located outside of the outer periphery of the storage medium and having the distal end portion thereof extending inward beyond the outer periphery of the storage medium. When the storage medium starts rotating, the head slider moves again to the data zone.
The CSS-type loading/unloading mechanism described above has been generally used in the prior art. Recently, however, an increased storage capacity has been required for the storage device, and in order to satisfy this requirement, the need has arisen to realize a higher data density by reducing the gap (the distance) between the head slider and the surface of the storage medium. To reduce the gap between the head slider and the surface of the storage medium, on the other hand, an improved smoothness of the surface is required for the storage medium. With improved smoothness of the surface of the storage medium, however, the problem is posed that the slider head is liable to be attached to the surface of the storage medium more easily, so that the load of the motor for resuming the rotation of the storage medium increases. This load, resulting from attachment of the head slider to the surface of the storage medium, is a problem especially in the case where a plurality of storage media are rotated with a single motor of the storage device to achieve an increased storage capacity of the storage device.
In contrast, the ramped-loading-type loading/unloading mechanism, in which the head slider and the surface of the storage medium are kept out of contact with each other when the storage medium is not in rotation, has the advantage that an additional load for starting the operation of the motor is not imposed on the motor for rotating the storage medium. Also, in view of the fact that the head slider is arranged on the ramp during non-rotation of the storage medium, the ramped-loading-type loading/unloading mechanism has a superior shock resistance and is suitable for use with a mobile device such as a mobile personal computer.
For the reasons described above, the current trend is toward wider use of the-ramped-loading type mechanism.
As shown in FIG. 10, in a head suspension 100 used with a ramped-loading-type loading/unloading mechanism, a tab 104 defined as a loading member formed integrally by deforming the support beam 102 protrudes beyond the center of the distal end of the support beam 102. When the storage medium stops rotating, the head suspension 100 is moved radially toward the outer periphery of the storage medium, and the tab 104 rides over the ramped surface of a slide-shaped ramp 106 extending over the storage medium beyond its outer periphery toward the center thereof. Thus the whole of the head suspension 100 is made to move away from the surface of the storage medium, so that a magnetic head slider mounted on a gimbal 108 supported on the head suspension 100 moves away from the surface of the storage medium (i.e. the unloading operation is performed). When the storage medium starts rotating, on the other hand, the head suspension 100 is moved to the outer peripheral portion of the storage medium by sliding down from the ramp 106 on the ramped surface thereof and approaches the storage medium in flying state (i.e. the loading operation is performed).
Further, as described above, the tongue portion of the gimbal with the head slider mounted thereon is pivotally coupled to the base portion of the gimbal through the pivotal portion arranged to the side nearer to the distal end of the support beam.
In the first step of the unloading operation, therefore, the tab contacts the ramped surface of the ramp, and the distal end of the head suspension moves away from the surface of the storage medium. Then, the flow-out end of the head slider, from which the air that has flowed into the gap between the head slider and the surface of the storage medium flows out, moves away from the surface of the storage medium. Finally, the flow-in end of the head slider positioned on the side opposite to the flow-out end thereof moves away from the surface of the storage medium. In the loading operation, by contrast, the flow-in end of the head slider contacts (approaches in flying state, to be more exact) the surface of the storage medium, and finally the flow-out end contacts (approaches in flying state, to be more exact) the surface of the storage medium.
Generally, the head suspension is arranged so that the storage medium moves from the proximal end of the head suspension toward the distal end thereof. Specifically, in the loading or unloading operation, the storage medium moves in such a direction as to be able to rub against the grain of the tongue portion of the gimbal. Should the smooth relative movement of the head slider to the storage medium be obstructed by the presence of foreign matter on the surface of the storage medium, therefore, the flow-in end of the head slider contacts the storage medium and an external force is exerted on the tongue portion of the gimbal to move it away from the support beam, sometimes resulting in damage to the head slider and to the storage medium. Also, the flow-in end of the head slider is lowered (comes closer to the storage medium) against the flow of the air into the gap between the head slider and the surface of the storage medium, and therefore the flying force becomes unstable, leading to the problem that the head slider and the storage medium are liable to contact each other.
Accordingly, the object of the present invention is to provide a magnetic storage device having a ramped-loading-type head suspension, in which in a loading or unloading operation of a magnetic head slider supported on the head suspension, the first step is to force a flow-in end of the head slider away from the surface of a storage medium thereby to stabilize the flying state of the head slider and thus reduce the possibility of damage to the head slider and to the storage medium due to contact in the loading or unloading operation.
In order to achieve the aforementioned object, according to one aspect of this invention, there is provided a head suspension, which includes a support beam having a distal end and a proximal end; a gimbal having a pivotal portion arranged to the side nearer to the distal end of the support beam and a free end arranged to the side nearer to the proximal end of the support beam, the gimbal being pivotally coupled to the distal end portion 20. of the support beam through the pivotal portion; and a loading member connected to the free end of the gimbal.
According to another aspect of the invention, there is provided a magnetic storage device, which includes the above-mentioned head suspension; a storage medium for storage of information; a magnetic head slider mounted on the gimbal of the head suspension in opposed relation to the storage medium; a driving unit for supporting the proximal end of the support beam of the head suspension and swinging the head suspension about the rotation axis; and a ramp having a ramped surface on which the loading member slides in a radial direction of the storage medium.
Preferably, in the head suspension, when the loading member of the head suspension is moved toward the support beam, the support beam and the gimbal of the head suspension are moved together after the gimbal moves toward the support beam about the pivotal portion.
Preferably, the gimbal has a portion extending the surface of the support beam.
Preferably, the loading member has a portion extending in the direction parallel to the surface of the gimbal.
The head suspension according to the present invention includes a loading member at the free end of the gimbal arranged to the side nearer to the proximal end of the support beam, so that when the loading member moves toward the support beam, the free end of the. gimbal moves toward the support beam about the pivotal portion arranged to the side nearer to the distal end of the support beam before the movement of the whole support beam. In the unloading operation, therefore, the flow-in end of the head slider bonded to the gimbal can move away from the surface of the storage medium first of all.
A further movement of the loading member toward the support beam causes the support beam and therefore the whole head suspension to move away from the surface of the storage medium. This movement results from the fact that the external force for moving the loading member toward the support beam is balanced with the reaction force generated by the spring effect due to the displacement of the gimbal and thereby transmitted to the support beam through the gimbal or the fact that the wing member of the gimbal contacts the support beam. Thus, the unloading operation can be performed while maintaining the flow-in end of the head slider farther away from the surface of the storage medium than the flow-out end thereof.
The loading operation is also similarly performed while maintaining the flow-in end of the head slider farther away from the surface of the storage medium than the flow-out end thereof. Thus, the flow-in end contacts the storage medium after the flow-out end of the head slider contacts the surface of the storage medium (or more exactly, flies in the air with a very small gap between the surfaces of the head slider and the storage medium).